Apparatus for molding hollow articles



June 13, 1933. E. KATZ APPARATUS FOR MOLDING HOLLOW ARTICLES Filed Nov. 18, 1931 mK VI mu 7 u E.

v Patented June 13, 1933 UNITED STATES PATENT OFF-ICE A BUG-EN KATZ, OF IBERLIN-OHARLOTTENBURG, GERMANY, ASSIGNOR TO CON- TAINER "CORPORATION, OF BOSTON, MASSACHUSETTS, A. CORPORATION OF MAINE APPARATUS FOR MOLDING HOLLOW ARTICLES Application filed November 18, 1931, Serial No. 575,823, and .in Germany November 13, 1930.

My invention relates to a method of, and apparatus for, molding hollow articles, and

uniformly, and the principal condition for this is uniform wall thickness of the articles.

It is an object of my invention .to so perform the method that sound articles of uniform wall thickness are obtained in a single mold although they are of various lengths.

It is another object of my invention to obtain uniform action of the drying agent throughout the length of the articles.

'The drying agents may be any gaseous fluids, air, other gas, steam, or a mixture of these media, and may be heated if desired.

Molding machines for articles "of the kind referred'to'a're old. For considerations of economy, the machines should be entirely or partly automatic. In such machines the mold is closed, charged with pulp through a pulp valve, whereupon the drying agent 1s.

admitted through a valve normally termed the air valve to expel the pulp, and finally the mold is opened for extracting the-more or less dried article. All this is performed within a predetermined and invariable period. The problem of making sound articles in various lengths with a given mold has not yet been solved. is a A simple solution of, the problem is presented by my invention as will be explained below but for better understanding the difficulties of the problem will first he set out.

tions are superheated while the base remains moist. I

Another difliculty is the lack of uniformity .in the settling of the fibres at the walls of the The fibres in the fibrine pulp tend to settle article which results also in unequal wall thickness. If, for instance, the mold was filled with pulp from above, the lower portion of the mold retained the pulp too long and the consequence was that the upper portion of the article became dry while its lower portion was still immersedin the pulp.

To eliminate this difliculty the residual pulp in the lower portion of the mold should be discharged as'rapidly as possible. It has been proposed to eject the pulp and the drying agent toward the bottom of the mold by a pipe opening near its bottom. By these means the wall thickness in the lower portion of the article is certainl reduced but the method cannot be applied to very thin pulps which are the only ones yielding articles having smooth inside walls, and may also cause unequal felting of the rapidly introduced pulp and even breaking through 'of the bottom of the article.

I have found that it is a mistake to speed up both the pulp and the drying agent but tle lat only the drying. agent should be speed- 6 P- With the object of my invention in mind, I admit the drying agent to the mold at a time which is predetermined in conformity with the length of the article. The overall molding period for a given article is not varied but the building-up of the pressure by which the pulp is'expelled' from the mold, is speeded up and varied with the length of the articlesso that by properly manipulating the air valve, articles of various lengths may be molded in a single machine andeven in a single mold.

The pulp is admitted to the mold under its own head, that is, without speeding up, while the drying agent is admitted under such conditions that it will perform its task of expelling the pulp under considerable acceleration.

The limit for the speed of the dryin a ent is determined by the condition that t e ottom of the article must not be broken through. Obviously the speed limit is higher for longer than for shorter articles. While for a short article. the bottom may-be damaged if the air valve is opened too abruptly it may be necessary for an article the length of which is, say, A

a this high hea six times that of the shorter one, to open the air valve ver abruptly as on the one hand the bottom 0 the article is protected by the high head of ulp while on the other hand requires rapid acceleration. Abrupt opening of the air valve may also become necessary for short articles if the molding machine is of the multiple type as described in U. S. Patent No. 1,845,804 as in 1 such machines the resistance of the pulp in the branches of the supply pipe is veryhigh 2nd must be counteracted by rapid accelera- For instance, if a short article has been molded and it is desired to mold a longer one, the drying agent is admitted at an earlier period and at a higherspeed for the longer article. Settling of too man fibres at the bottom of the mold is revente and the residual pulp is rapidly ischarged while on the other hand the high head of pulp in the mold which is initially present prevents damage to the article and, in particular, breaking through of its bottom.-

The drying period is desired substantially of equal length for the upper and lower portion of the article but all the same the drying period previously required for the upper portion is a little longer. This is prevented and uniform action of the drying agent throughout thelength of the article is obtained by providing t e apparatus in which my method is performed, with means for backing up the flow of the agent from the upper portions of the mold.

In the accompanying drawing a molding machine in which m method may be performed, is illustrate diagrammatic-ally by way of example.

Referring now to the drawing, a is a foraminous mold, b is a supply pipe for pulp and drying agent, 0 is a pulp valve, and d is an air valve at the upper end of the pipe I). e is a cowl surrounding the upper portion ofthe mold for backing up the escaping drying agent, and f is a discharge pipe at the lower end of the cowl.

The cowl e may be modified as shown broken awayat the right where its lower end k is constricted and increases the backing-up like a nozzle.

Openings 5 may be made in the cowl for preventing excessive backing-up at certain regions.

In the machine illustrated by way of example, the valves 0 and d are operated manually. In an automatic or semi-automatic machine,

7 means such as hydraulic members may be provided for controlling the two valves 0 and d and for regulating and interrelating their opening periods in conformity with the length of a given article. By the same hydraulic or other control means the valves may be opened and closed more slowly or more rapidly.

A. simpler and cheaper control is effected by providing cams for operating the valves. One or more cams (not shown) may be provided on a shaft which rotates at a speed adapted to the operating velocity of the machine, and preferably the cams, and particularly those for controlling the air valve, are adjustable or equipped with exchangeable parts. In a machine of this kind it is possible to adjust the machine for each kind of article to be molded.

The hood 6 or 9 may be of sheet metal, and of any suitable size. It may be made of perforated sheet metal, and the upper portion of the mold a may be entirely enclosed by the cowl. Whatever may be the design of the cowl, its action is that the drying agent, preferably heated, acts more intensely and at higher speed on the bottom portions of the article which require more effective drying. If the cowl is made with a downward extension as shown at h a portion of the heat from the backed-up agent is transferred to the article in the mold a The cowl may also be so designed that its backing-up action is increased during the drying operation. While the upper portion of the article is still moist the backing-up action is lessbut is increased as the drying at the upper portion proceeds, for instance, by closing, or partly closing the openings '5.

In the manner described molded articles of any size and wall thickness may be molded in a single machine and extracted from the machine after a short time in a condition of such dryness that they need not be handled but are delivered to a conveyer or the like from the mold. They will not undergo deformation and the percentage scrap is low.

Other advantages of my method and apparatus are:

Saving of fuel and dryin agentas its heat is better utilized by exchang with the article in the cowl e or g, so that for the same quantity of agentper unit of time the articles are drier or, for the same degree of dryness, the amount of agent per unit of time is less.

My method and apparatus permit the use of textile materials which are difiicult to dehydrate, for molding. Pure cellulose or textile fibres are much harder to dry than, for inlary moisture. On the other hand, these materials yield abetter product, such as woodless paper etc. As molded articles they are stronger and of better appearance than others, and particularly strong if the material is finely ground. The drying of molded articles as performed heretofore did not permit to obtain articles of pure cellulose in substantially dry condition, but only articles consisting sub-- stantially of lignine ground to brittleness.

][ claim: 1. An' apparatus for moldmg hollow Ill articles of fibrine pulp in a foraminous moldj'i comprising means for admitting pulp an drying agent to said mold, and means for bacling up the drying agent as it leaves the mol 2. An apparatus for molding hollow articles of fibrine pulp, in a foraminous mold comprising means for admitting pulp and drying agent to said mold, and means for backing up the agent and for conducting it along said mold as it leaves the mold.

3. An apparatus for molding hollow articles of fibrine pulp in a foraminous moldi comprising means for admitting pulp an drying. agent to said mold, means for back ing up the drying agent as 1t leaves the mold, and means for varying the backing-up action of said means.

4. An a paratus for molding hollow articles of brine pulp in a foraminous mold, comprising means for admitting pulp and drying agent to said mold, and a cowl which surrounds the upper portion of said mold and is open at its lower end.

5. An a paratus for molding hollow articles of brine pulp in a foraminous mold, comprising means for admitting pulp and drying agent to said mold, and a cowl having an opening in its wall which cowl surrounds the upper portion of said mold and is open 8."

its lower end.

6. An a paratus for molding hollow articles of brine pulp in a foraminous mold comprising means for admitting. pulp and drying agent to said mold, and a cowl which surrounds the upper ortion of said mold and is open and restricte at its lower end. A

In testimony whereof I aflix my signature.

EUGEN KATZ. 

